Oxidation inhibited lubricants



United StatesPatent O I "3,185,645 7 Y OXIDATION INHIBITED LUBRICANTS James 0. Clayton, Berkeley, Calif., assignor to California -Research Corporation, SanFrancisco, Calif., a corporation of Delaware 3N0 Drawing, Filed Sept. 28,1962, Ser. N 227,042

5 Claims. oi.- ass-46.7

This invention pertainsto lubricating oil compositions having incorporatedtherein metal-freedetergents. These particular deter'gentsare also elfectiv'e as oxidation inrumors. H

Present high speeds and high compression ratios. When used in day internal combustion engines operate at the so-called city, stop-and-go driving, which includes the greater part of the driving-conditions for a large percent. age of todays automobiles, the internal combustionengines do not reach the most efficient operating temperature. Under city driving conditions, large amounts ofpartial oxidation products are formed, and reach thedcrankcase ofthe engine by blowing past the. pistonrings. Most of the. partial oxidation products are oil-insoluble, tending ;-to form deposits on the various operating parts of theenffgine, such as-the pistons, piston rings, etc. -For the purpose'of preventing the deposition of these products on the yarious engine,parts ,i it is necessary to incorporatedetergents in the lubricating oil compositions, thus keeping these polymeric products dispersed in a condition un favorable for deposition on metals.

For the most part, the detergents which are added tocrankcase oils to reduce this formation;v of sludges and varnishes are metal organic compounds, particularly those compounds wherein the metal is linked to an organic group through an oxygen atom. Although these metalcontaining organiccompounds have some effectiveness as 1 detergents for dispersing theprecursors of the deposits within the oil itself rather than permitting them to form" as deposits on theengine parts, they have the disadvantage of forming ash deposits in the engine. =These ash deposits lower engine performance by ,fouling spark plugs and valves, and contributing to pre-ignition.

I It is a particular object of this invention to provide lubricating oil' compositions having incorporated therein metal-free detergents which are also effective as oxidation inhibitors. Thus, these new additives inhibit the oxidation of lubricating oil compositions and also disperse the undesirable polymeric products which are formed.

Therefore, in accordance with this invention,it has been found that lubricating oil compositions particularly useful for heavy duty service are obtained by incorporating therein a product-obtained by reacting an alkenyl succinic an- 3,185,645 Patented May 25, 1965 ice atoms. Examples of alkenyl radicals include n-decenyl, n-hexadecenyl, propylene tetramen'butylene trimer, propylene polymers containing from 50 to 200 carbon atoms, and polymers of mixtures of l-butene and isobutene having from 50 to 200 carbon atoms.

The dihydrocarbyl dithiophosphoric acids which are reactants herein can be representedby the formula phosphoric acid, diethyldithiophosphoric acid, di-n-propyl dithiophosphoric acid, di-isopropyldithiophosphoric acid, di-nbutyldithiophosphoric acid, diisobutyldithiophosphoric acid, n-butyl-n-amyldithiophosphoric acid, di-secamyldithiophosphoric acid, methyl n-hexyldithiophosphoric acid, isobutyl-n-hexyldithiophosphoric acid, di-noctyl-dithiophosphoric acid, methylcyclohexyl. dithiophosphoric acid, methylcyclohexyldithiophosphoric acid, dicyclohexyldithiophosphoric acid, methylphenyldithiophos- .phoricacid, diphenyldithiophosphoric acid, di-(amylphenryl)dithiophospho ric. acid, di (hexadecylphenyl)dithiophosphoric acid, etc.

, The polyalkylene polyamines, which contribute the imide and the basic nitrogen atoms of the reaction products herein, are derived from polymers of ethylene or propylene, such as polyethylene polyamine, and polypropylene ,polyamines'. Such polyalkylene polyamines may be represented by the formula wherein the R represents the divalent radical ethylene or propylene, and'x is a number having a value from 1 to 10 or more. Examples of these polyalkylene polyamines include diethylene triamine, triethylene tetramine, tetrahydride, a Tdihydrocarbyl dithiophosphoric acid, and a polyalkylene polyamine p,

' By the use of lubricating oil compositions containing the reaction products described herein, diesel and gasoline engine products remain remarkablyfree of deposits and varnish even under severe operating conditions. 7

, The alkenyl succinic anhydride reactants herein are of the formula I e era-o wherein R is a hydrocarbon radical having from '10 to 200 carbon atoms therein, preferably from 5010 200 carbon ethylene pentamine, pentaethylene hexamine, dipropylene trian'iine, dipropylene tetramine, tetrapropylene pentamine, pentapropylene hexamine, di(trimethylene)triamine, tri(trimethylene) tetramine, tetra-(trimethylene)- V pentamine and penta- (trimethylene)hexamine.

There is no one particular reaction mechanismwhich is used to produce reaction products which are useful herein in lubricating oil compositions as oxidation inhibitors and detergents according to this invention. 'An alkenyl succinic anhydride, a polyalkylene polyamine, and a dihydrocarbyl dithiophosphoric acid can be mixed together in the desired amounts and reacted; or a poly alkylene polyamine may bereacted with a dihydrocarbyl dithiophosphoric acid, and the resulting product then re acted with an alkenyl succinic anhydride, or the alkenyl succinic anhydride may be reacted with the dithiophosphoric acid, followed by the reaction with the polyalkylene polyamine.

The rnol ratio of dithiophosphoric acid to polyamine 7 can vary from (X --l) :1 to 111, wherein X represents the number of titratable amine groups in the .polyalkylene anhydride mol ratio is in the range of 0.8:1 to 1:1.

When the initial reactants are an anhydride and a dithiophosphoric acid, the mol ratio of anhydride to dit-hiophosphoric acid can vary from 0.521 to 1:1. Preferably,

the mol ratio of anhydride to dithiophosphoric acid is 1:1.

In the reaction herein to form the desired reaction prodncts, the reaction temperature can vary from 70 F. to 400 F., preferably from 210 F. to 310 F. In the reaction of polyalkylene polyamine and the dithiophosphoric acid, the preferred reaction temperature is from 70 F. to about 200 F., followed by a temperature sufiicient to evolve H S in the reaction with the alkenyl succinic anhydride. j

No theory is postulated herein as to the structure of the reaction products herein. It is recognized, however, that the final reaction temperature is a temperature sufiicient to evolve hydrogen sulfide from the reaction mixture.

Lubricating oils which can be used asbase oils to form lubricating oil compositions include a wide variety of lubricating oils, such as naphthenic base, paraffin base, and mixed base lubricating oils, other hydrocarbon lubricants, e.g., lubricating oils derived from coal products, and synthetic oils, e.g., alkylene polymers (such as polymers of propylene, butylene, etc., and the mixtures thereof), alkylene oxide-type polymers (e.g., propylene oxide polymers) and derivatives, including alkylene oxide polymers prepared by polymerizing the alkylene oxide in the presence of water or alcohols, e.g., ethyl alcohol, dicarboxylic acid esters (such as those which are prepared by esterifying such dicarboxylic-acids as adipic acid, azelaic acid, 'suberic acid, sebacic aid, alkenyl succinic acid, fumaric acid, maleic acid, etc., with'alcohols such as butyl alcohol, hexyl alcohol, 2-ethyl hexyl alcohol, dodecyl alcohol, 'etc.), liquid esters of acids of phosphorus, alkyl benzenes "(e.g., monoalkyl benzene such as dodecyl benzene, tetradecyl benzene, etc.), and dialkyl benzenes (e.g., n-nonyl 2-ethyl hexyl benzene); polphenyls (e.g., biphenyls and terphenyls), alkyl biphenyl ethers, polymers of silicon (e.g., tetraethyl silicate, tetraisopropyl silicates, tetra (4-rnethyl-2-tetraethyl)silicate, hexyl (4-methyl-2-pentoxy)disiloxane, poly(methyl)siloxane, poly(methyl-phen- 'yl)siloxane, etc. Synthetic oils of the alkylene oxide-type polymers which maybe used include those exemplified by the alkylene oxide polymers.

The products described herein can be used in oils in amounts of 0.1% to 40% by weight, preferably 0.1% to more preferably 1% to 10%.

The following examples illustrate the formation of the reaction product useful herein as oxidation inhibitors and detergents.

EXAMPLE I 72 grams (0.38 mol) of tetraethylene pentamine was charged to a reaction vessel with continued agitation, and blanketed with nitrogen To this tetraethylene pentamine there was added 409 grams (0.38 mol) of a 50% lubricating oil solution of di(alkylphenyl)dithiophosphoric acid in which the alkyl radicals were derived from propylene polymers having an average of 13 carbon atoms. The temperatures of the reaction vessel rose from 80 F. to 155 F. The reaction mixture was heated to 200 F., after which there was added 1005 grams (0.47 mol) of a 48% lubricating oil solution of polyisobutenyl succinic anhydride which had been preheated to 200 F. The alkenyl radical of the isobutenyl succinic anhydride con tained an average of 66 carbon atoms. The reaction mixture was heated at temperatures in the range of 305-3 15 F. for 2 hours while a solid stream of nitrogen was blown through the mixture.

' Nos. intermediate in F was blanketed with nitrogen.

from ambient temperatures to F., after which the -mixture was heated to 200 F., after which there was 4 Upon analysis, it was found that the resulting lubricating oil composition contained the following:

Table I Weight percent Basic nitrogen 0.83, 0.83 Nitrogen 1.71, 1.72 Phosphorus 0.84, 0.84 Sulfur 1.16, 1.15 Acid No., mgs. KOH/gram 14.91, 13.08

EXAMPLE II A mixtureof 103 grams (1 mol) of diethylene triamine was reacted at ambient temperature with 270 grams (1 mol) of isobutyl-n-hexyl dithiophosphoric acid. This reaction product was heated with 322 grams of n-hexadecenylsuccinic anhydride to 325 until the water of reaction had been removed. I

EXAMPLE III 818 grams (0.76 mol) of a di(alkylphenyl)dithiophosphoric acid (wherein the alkyl groupwas derived from a polypropylene having an average of 13 carbon atoms) was rapidly added with agitation to 144 grams (0.76 mol) of tetraethylene pentamine wherein the reaction vessel The temperature rose added 1980 grams (0.93 mol) of a polyisobutenyl succinic anhydride wherein the polyisobutenyl radical had a molecular weight of about 1,000, preheated to 200 F. The reaction mixture was heated to 310 F. for a period of 2 hours. Hydrogen sulfide was evolved during the entire 2 hour reaction period.

The following analytical results were obtained on the reaction product.

Wt. percent Phosphorus 0.85 Nitrogen 1.72 Basic nitrogen 0.92 Sulfur -Q. 1.43 Acid No 17.1

EXAMPLE IV 113 grams (0.38 mol) of a mixed dialkyl dithiophosphoric acid, wherein one of the alkyl radicals contained 4 carbon atoms and the second alkyl radical contained 6 carbon atoms, was added to 72 grams of tetraethylene pentamine (0.38 mol) in a reaction vessel blanketed with 'mixture contained 1.09% by weight of phosphorus, and

1.77% by weight of sulfur. The dialkyl dithiophosphoric acid itself originally contained 11.2% phosphorus and 23 .4% sulfur.

Table II hereinbelow presents data obtained with lubricating oil compositions containing the reaction product of Example III hereinabove.

The test was made in a Caterpillar L-1 engine according to the Supplement I conditions (for a period of the hours noted) as described in the Coordinating Research Council Handbook, January 1946.

The PD Nos. refer to the piston discoloration rating. After the engine test, the three piston lands are examined visually. To a piston land which is completely black is assigned a PD No. of 800; to one which is completely clean, a PD No. of 0; to those intermediate between those completely black and completely clean are assigned PD proportion to the extent and degree of darkening.

. The GD Nos. refer to the percentage deposit in the piston ring grooves; that is, a evaluation being a clean groove, and a 100 evaluation being a groove fullof polypropylene having an average of 13 carbon atoms.

Tableli Additive: 1. Reaction product of Example III, wt. percent- 0.0 0.0 2. Dithiophosphate:

(A) mM./kg. (B) mMJkg.

Test results 120 hours V 120 hours Top GD No a9 PD Nos., Land 800, 800, 800

1 Mfllimols of zinc per kilogram of finished lube oil.

Table III hereinbelow presents oxidation test results for lubricating oil compositions describedherein. The oxidation test measures the time (hours) for the agitated oil sample to take up 1 liter of oxygen per grams of oil sample at 340 F. a i

The base oil was a California paraifinic base oil having a viscosity of S00 SSU at 100 F.

Each of the compositions described in Table III con- 'tained the same amount of total phosphorus, thatfis,

24.4 n1M./kg. V

, Table III I Oxidation Test,

hours 0.25

Composition:

(1) Base oil (2) Base oil+6.81 wt. percent 1 Prod. of Ex. IV hereinabove (3) Base oil+8.6 wt. percent 1 Prod. of Ex. III hereinabove 10.7 (4) Base oil+3% Succinimide +12 mM./kg. dithiophosphate A (5) Base oil+3% Succinimide +12 mM./kg.

dithiophosphate B 4.5 Equivalent to 3.0% by weight of Succinimide 2 The alkenyl suecinirnide of tetraethylene pentamine, wherein the alkenyl radical contained 66 carbon atoms.

I claim: j 1. A composition of matter comprising a major proportion of an oil of lubricating viscosity and from 0.1% to 40% by weight of a product obtained by reacting (1) an alkenyl succinic anhydride having from 50 to 200 carbon atoms in said alkenyl radical, (2) a polyalkylene polyamine of the formula NH R(NHR) NH wherein R is a divalent radical selected from the group consisting of ethylene and propylene and x i a number having a value from 1 to 10, and (3) a dihydrocarbyl dithiophosphoric acid of the formula n i R-O-$SH wherein R and R are hydrocarbon radicals each having from 4 to 20 carbon atoms with a combined total of to 40 carbon atoms, wherein the mole ratio of said 7 6 i dithiophosphoric acid of said polyamine is from "(X-1) :1 to '1: 1, wherein .X is the number of titratable amine groups in said polyamine, wherein the mole ratio of said wherein R is a divalent radical selected from the group consisting of ethylene and propylene and x is a number having a value from 1 to 10, and a dihydrocarbyl dithiophosphoric acid of the formula wherein R and R are hydrocarbon radicals each having from 4 to 20 carbon atoms with a combined total of 10 to 40 carbon atoms,said reaction being at temperatures from 70 F. to200 F. followed by (2) reacting the product of (1) with an alkenyl succinic anhydride at temperatures'of 210 F. to 400 F. sufiicient for evolution of hydrogen sulfide wherein said alkenyl group contains from 50 to 200 carbon atoms, wherein the mole ratio of said dithiopho sphoric acid to said polyamine is from (X1):1 to 1:1, wherein X is the number of titratable amine groups in said polyamine, wherein the mole ratio of said polyamine to said anhydride is from 015:1 to 1:1. 3. The composition of matter of claim 2 wherein said polyamine is tetraethylene pentamine.

4. A composition of matter comprising a major proportion of an oil of lubricating viscosity and from 1% to 10% by weight of a product obtained by reacting (1) an alkenyl succinic anhydride having from 50 to 200 carbon atoms in said alkenyl radical, (2) a polyalkylene polyamine of the formula wherein R is a divalent radical selected from the group consisting of ethylene and propylene and x is a number having a value from 1 to 10, and (3) a dihydrocarbyl dithiophosphoric acid of the formula 5. The composition of matter of claim 4 wherein said polyamine is tetraethylene pentamine.

References Cited by the Examiner UNITED STATES PATENTS 2,809,934 10/57 Alford et a1 252--32.7 2,973,323 2/61, Millikan et al. 25232.7 2,995,568 8/61 Malz et a1. 260-3265 3,018,247 1/62 Anderson et a1. 252-32] 3,058,910 10/62 Culmer 252-32.7 3,074,990 1/63 Cyba 252-32.7

DANIEL E. WYMAN, Primary Examiner. 

1. A COMPOSITION OF MATTER COMPRISING A MAJOR PROPORTION OF AN OIL OF LUBRICATING VISCISITY AND FROM 0.1% TO 40% BY WEIGHT OF A PRODUCT OBTAINED BY REACTING (1) AN ALKENYL SUCCINIC ANHYDRIDE HAVING FROM 50 TO 200 CARBON ATOMS IN SAID ALKENYL RADICAL, (2) A POLYALKYLENE POLYAMINE OF THE FORMULA 